Ultrasonic nozzle measuring system

ABSTRACT

This is a system for ultrasonically measuring the minimum areas of flow between spaced apart partitions wherein the partitions are cooperatively arranged to define individual nozzles. The system may include an apparatus for inserting and orienting an ultrasonic probe between the spaced apart partitions.

nited States Patent [191 McKnight et al.

11 3,732,946 1 May 15, 197 3 ULTRASONIC NOZZLE MEASURING SYSTEM Inventors: Edmund McKnight, Nahant; Michael Lee Tuttle, Ipswich, both of Mass.

Assignee: General Electric Company, Lynn,

Mass.

Filed: May 25, 1971 Appl. No.: 146,671

U.S. Cl ..l81/.5 NP, 73/67.8, 73/457 Int. Cl. ..GOlb 17/00 Field of Search ..l81/.5 BE, .5 NP;

[56] References Cited UNITED STATES PATENTS 3,614,891 10/1971 Nolte ..l8l/.5 BE 3,378,097 4/1968 Straus et al. ..l8 l/.5 BE 3,554,014 1/1971 Berg et al. ..73/67.8

Primary ExaminerRobert F. Stahl Assistant Examiner.l. V. Doramus Attorney- Edward S. Roman & Derek P. Lawrence ABSTRACT This is a system for ultrasonically measuring the minimum areas of flow between spaced apart partitions wherein the partitions are cooperatively ar ranged to define individual nozzles. The system may include an apparatus for inserting and orienting an ultrasonic probe between the spaced apart partitions.

6 Claims, 8 Drawing Figures PATENTED 3.732.946

SHEET 3 OF 4 5 M/(A AQZ Z. 707715 ZM/WM 1 ULTRASONIC NOZZLE IVIEASURING SYSTEM BACKGROUND OF THE INVENTION This invention relates to an ultrasonic nozzle measuring system and more particularly to an ultrasonic system for measuring minimum nozzle flow area.

Nozzle assemblies of the type including a plurality of circumferentially spaced apart airfoil partitions extend.- ing in generally radial directions from an inner annular band to an outer annular band form an integral part of a gas turbine engine and are well known to the art. Each pair of adjacent partitions defines an individual flow path and the rate of gas flow between each pair of adjacent partitions in a nozzle assembly is influenced by the minimum cross-sectional area across each flow path. The minimum flow areas between all the pairs of partitions of the nozzle assembly must be substantially uniform in order to insure high engine efficiency, reliability, and durability. Therefore, it is of primary concern that the minimum flow areas between all pairs of nozzle partitions be accurately measured during the manufacturing process.

Difficulties, however, have been experienced in measuring nozzle flow areas, and of the many methods now known to the art none has yet proved to be both accurate and economical. Mechanical measuring techniques range from hand held dial indicators to more sophisticated machinesv which automatically measure and record areas. However, mechanical measurement techniques have proved successful only for larger nozzles. For smaller nozzles, inaccuracies arise due primarily to the inability to improve the accuracy of the dimensional measurement as required to maintain a small percentage error in area measurement.

Water flow measuring techniques were introduced in an effort to improve the accuracy and repeatability of the mechanical measuring techniques. The water flow technique is based on the theoretical assumption that for a fixed head of water flowing through an orifice, the area of the orifice is inversely proportional to the time required for a given quantity of water to pass through the orifice. Constants of proportionality may be predicted for the case of a simple orifice; however, the nozzle presents a substantially more complicated situa tion. The nozzle induces large pressure gradients in the flow, and impingement of the swirling flow discharged from the nozzle on surrounding structure causes a back pressure within the nozzle which affects the water flow time, all of which must be compensated for in order to obtain an accurate measurement. 7

Air flow measuring techniques which flow cold air through a nozzle have been found to be very accurate. In practice, however, the high cost of conducting air flow measurements limits their practicality to development use only.

Therefore, it is an object of this invention to introduce a new measuring technique for determining nozzle flow areas in a reliable, accurate and economical manner, while maintaining precision repeatability.

It is also an object of this invention to apply ultrasonic measuring techniques to overcome the aforementioned difficulties of the prior art in measuring nonle flow areas. I

It is a further object of this invention to provide a novel apparatus for inserting and orienting an ultrasonic probe between the opposing partitions of a conventional noale assembly so asv to facilitate ultrasonic measurement of the noale flow area.

SUMIVIARY OF THE INVENTION The invention provides a system for ultrasonically measuring distances between spaced apart partitions wherein the partitions cooperate to define a nozzle, and the distances so measured may be utilized for calculation of the minimum nozzle flow area between the partitions. The system includes a tank filled with a liquid medium within which the partitions are submersed. A means for generating electrical signals is provided for electrical connection to ultrasonic transducers of a probe. The transducers convert the electrical signals into ultrasonic wave energy and convert any reflected ultrasonic wave energy back into electrical signals. There is also provided a means for converting the time required for reflected ultrasonic signals to return to the transducers into a representation of distance. The probe is moved between the Partitions by a suitable means so as to automatically seek the distances required for measuring the minimum nozzle flow area.

One apparatus for inserting and orienting the probe between the spaced apart partitions includes a lever arm rotatably retained with respect to a supporting member. The lever arm includes a cam track on at least one side thereof, such that a supporting plate is disposed for guidance along the cam track. The probe is rotatably coupled to the supporting plate means for rotation about its central axis. Initial insertion of the probe between the partitions is accomplished by rotation of the lever. The probe is then further oriented between the partitions by moving the supporting plate means along the cam track in combination with rotation of the lever arm.

DESCRIPTION OF THE The invention maybe better understood upon reading the following description of the preferred embodiment in conjunction with the accompanying drawings in which:

FIG. 1 shows a partial perspective view of a nozzle assembly of the type commonly used in gas turbine ennes. FIG. 2 shows a perspective view of two partitions which are cooperatively arranged to form one of the nozzles of the noule assembly of FIG. 1.

' FIG. 3 shows a cross-sectional view of the two partitions of FIG. 2.

FIG. 4 shows an integrated system for ultrasonically measuring the individual nozzle areas. FIG. 5 shows a perspective view of a probe adjusting apparatus for inserting and orienting a probe between two spaced apaitpartitions, both of which are cooperatively arranged to form a nozzle.

FIG. 6 shows a side view of the apparatus of FIG. 5 illustrating difierent positions of mechanical movement for the probe adjusting apparatus.

FIG. 7 shows another side view of the apparatus of FIG. 5 illustrating other positions of mechanical movement for the probe adjusting apparatus.

FIG. 8 shows a partial front view of the apparatus of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is shown at 10a portion of a conventional nozzle assembly of the type suitable for incorporation within a gas turbine engine. Noule assembly is shown as including an inside annular band 12 and an outside annular band 14. Circumferentially spaced partitions 16, which typically approximate the shape of an airfoil, are disposed between bands 12 and 14. The partitions 16 extend in' generally radial directions and are fixedly attached to the bands 12 and 14.

Referring now to FIG. 2, in conjunction with FIG. 1, there is shown in substantial detail two partitions 16 of the nozzle assembly 10, each of which is specifically designated by the reference letters A and B respectively. The outer radial surface of each partition A and B is shown at 20 and is in fixed abutting relation with the outside annular band 14. The inner radial surfaces of each partition A and B are shown at 18 and are in fixed abutting relation with the inside annular band 12. One face of each partition generally approximates a concave surface 22 with the opposing face approximating a convex surface 24, such that the convex surface 24 of each partition is opposite the concave surface 22 of an adjacent partition. Each pair of adjacent partitions together with the inner band 12 and the outer band 14 cooperates to form a nozzle. Gas flow between the partitions, represented by the flow arrows, is shown as impinging on the leading edges 26 of the partitions 16 and exiting past the trailing edges 27.

The plane of minimum nozzle flow area between two adjacent partitions A and B is commonly referred to in the art as the nozzle area. The nozzle area between partitions A and B lies in a plane which is orthogonal to the convex surface 24 of partition A, and which intersects substantially close to the trailing edge 27 of partition B. The dimensional limits for the nozzle area are shown by the arrows labeled outer, mid, inner and L wherein outer, mid and inner designate the outer band width, mid-span band width and inner band width respectively and L designates the length.

A close approximation of the actual nozzle area may be calculated according to a standard mathematical approach referred to as Simpsons Rule. Because the con vex surface 24 of partition A and the concave surface 22 of adjacent partition B lie in planes which converge in radial directions, the width from near the trailing edge of partition B to the closest point on the convex surface 24 of partition A, when measured near the outside annular band 14, is larger than when measured near the inside annular band 12. Therefore, the three width measurements designated as the outer band width, the mid-span width and the inner band width must be made and properly weighted in order to accurately define the actual nozzle area. The mid-span width measurement is made from a point near the trailing edge of partition B, which is equidistant from both the inside annular band 12 and the outside annular band 14, to the closest point on the opposing convex surface 24 of partition A. The inner band width and outer band width measurements are made in close proximity to the inside annular band 12 and the outside annular band 14 respectively. The length measurement for calculating the nozzle area is essentially a-radial measurement from the inside annularband 12 to the outside annular band 14. An average width measurement is calculated according to Simpson s Rule by multiplying the mid-span width measurement by 4 and subsequently adding the outer band width measurement, and the inner band width measurement, and then dividing the result by 6. The actual nozzle area may then be calculated by multiplying the average width as found from Simpsons Rule by the length measurement.

In order to manufacture an efiective and suitable noule assembly for use within a gas turbine engine, uniform nozzle areas must be maintained between all adjacent partitions while also maintaining control over the total cumulative flow area of all the nozzles of the nozzle assembly. This invention applies the techniques of ultrasonic measurement to determining nozzle areas so that highly accurate nozzle area measurements may be rapidly repeated in an efficient manner thereby insuring uniform nozzle area during manufacture.

Referring now to the cross-sectional view of FIG. 3, there are shown the two adjacent partitions A and B of FIG. 2 submersed in a suitable fluid such as water. A dual pencil probe 30 is shown as including two opposing ultrasonic transducers 32, 32', both of which are piezo-electric crystals arranged out of phase with each other for beaming ultrasonic wave energy in opposing directions. An electrical connection is made to the ultrasonic transducers 32, 32' in the usual manner through cables 33, 33 which extend from the transducers to an ultrasonic pulse generator 58 as shown in FIG. 4. The ultrasonic pulse generator 58 applies radio frequency pulses to the transducers 32, 32' by means of the cables 33, 33 respectively, whereupon the transducers convert the pulses into ultrasonic wave energy. The transducers 32, 32 also convert reflected ultrasonic wave energy back into electrical signals which are then returned along cables 33, 33 and amplified by a suitable amplifier 64 as is also shown in FIG. 4. The output signals from the amplifier 64 may be applied to a suitable display device such as an oscilloscope 62, in a manner to be subsequently described.

The trailing edges of nozzle partitions generally do not terminate in sharp edges about which the ultrasonic beams generated by the transducers may be readily trained. In practice, the trailing edges will be radiused to form a curvilinear plane of revolution about a central axis such as 34. The axis 34 extends from the inside annular band 12 to the outside annular band 14 and is shown in FIG. 3 as lying in a direction substantially normal to the plane of the drawing. The line of intersection between the curvilinear plane of revolution about the axis 34 and the concave surface 22 is designated at 35 and it is from this line that the minimum nozzle flow area width measurements should be made rather than from the exact trailing edge.

Phantom line 37 and phantom arc 39 represent nominal paths along which the dual pencil probe 30 may be moved in order to orient the ultrasonic beams of the transducers 32, 32 onto the plane of minimum nozzle flow area. Phantom line 37 is also an arc; however, it has such a large radius in comparison with the radius of arc 39 that it may be treated as a straight line in the area between the partitions. A probe adjusting means, shown generally at 48 in FIG. 4 and to be subsequently described in full detail, provides fixturing means for moving the probe 30 about the subject paths.

For convenience, the angle of the nominal path of insertion 37 may be arbitrarily established to approximate the chord angle of the partitions 16. However, the initial angle of insertion for the probe along phantom line 37 is not critical, and as will become apparent, the transducers can be subsequently oriented to the plane of minimum nozzle flow area for almost any initial angle of probe insertion. Ultrasonic measuringis commenced by inserting the dual pencil probe along the path 37 until an echo signal first appears for the ultrasonic energy reflected from the trailing edge of partition B, whereupon the probe will occupy the position shown in phantom lines. As can be seen from the drawing, the ultrasonic energy beamed from transducers 32, 32 does not yet lie in the plane of minimumnozzle flow area, and therefore subsequent adjustment of the probe orientation is required. 7

Incremental movement of the probe 30 along the arcuate path 39 in combination with further movement in either direction along the path 37 in a manner so as to always seek the shortest distance between the line of intersection 35 and the convex surface 24 of partition A will result in alignment of the probe axis normal to the plane of the nozzle area, -as illustrated by the solid line probe. The arcuate path 39 may have a center of radius about the line of intersection 35 so as to reduce the number of incremental seeking movements required to orient the probe normal to the plane of the nozzle area.

The minimum nozzle flow area width measurement may be ultrasonically made by observing the time required for the respective echoes to return to the transducers 32, 32. Adding together the two distances, together with the distance between transducers, will then provide the required width measurement. As previously discussed, three width measurements must be made in order to accurately determine the nozzle area. Therefore, the probe 30 must be translated in a line normal to the plane of the drawing in order to make the outer band width, the mid-span width, and the inner band width measurements.

After the three width measurements have been made, means must be provided for rotating the probe 90 degrees about its central axis in order to make the required length measurement. All the measurements for determining the nozzle area by Simpsons Rule may be made through the use of one dual pencil probe.

Referring now to FIG. 4, there is shown a system by which the individual nozzle areas of a nozzle assembly may be automatically measured by ultrasonic techniques. A tank 36 is shown filled with a fluid, preferably water. Within the tank 36 there is included a turntable 38 rotatably mounted to the bottom surface of the tank. The turntable 38 is supported for rotation with respect to the tank by means of shaft 40, journalled within the bottom of the tank and extending therethrough. The shaft 40 may include a pulley 42 at the outside end thereof, which may be further connected to a stepping motor 46 by means of a belt 44 so as to provide rotation of the turntable 38 through belt 44, pulley 42, and shaft 40. A nozzle assembly is removably fixtured to rotate with the turntable 38.

Dual pencil probe 30 is coupled to the probe adjusting means 48 which, through a series of incremental movements, directs the probe 30 to seek the four measurernents described for determining each nozzle area. A probe support means 50 is provided for suspending the adjusting means 48 within tank 36. The other end of supporting means 50 is connected to a carriage 52 which may be moved along the rim of tank 36 by means of wheels 54. The wheels 54 of carriage 52 provide a means of translating the probe across the tank so that nozzle assemblies having partitions slanting in both clockwise and counterclockwise directions may be accommodated by the system. Also, height adjusting screws 55 may be provided at the ends of carriage 52 for adjusting the vertical position of the carriage 52 with respect to the rim of tank 36. The screws 55 provide means by which the relationship between the probe adjusting means 48 and nozzle partitions 16 may be adjusted.

Ultrasonic energy is supplied to the dual pencil probe 30 by means of the ultrasonic pulse generator 58 which further serves to trigger a range time base 60. The initial ultrasonic pulses, together with the returned echo signals, are fed to the amplifier 64 from which they may be applied to the vertical plates of the oscilloscope 62 for display purposes.

A sawtooth output from the range time base 60 may be applied to the vertical plates of the oscilloscope 62 to provide a suitable time base to which the sonic pulses may be correlated. The amplifier 64 may also channel the ultrasonicpulses to a suitable recorder 66 through which the pulses are integrated for automatic calculation of noule area through Simpson s Rule, with a permanent record of each nozzle area provided by the recorder chart. A suitably programmed computer 68 may also be provided to automatically step motor 46 after each nozzle area measurement has been completed, together with control signals for sequencing the adjusting means 48 through the discrete movements required to make each length and width measurement. The recorder ,66 may also provide ultrasonic feedback to the computer 68 wherein the feedback signals modify, amplify, or otherwise update the computer output as influenced by the incoming ultrasonic information. In the event that a nozzle area measurement does not meet the required specification, an error signal may be provided to automatically reject the nozzle assembly.

Referring now to FIGS. 5 through 8, there is shown in substantial detail an assembly for the probe adjusting means 48. This assembly directs the movement of the probe 30 through a series of movements so that the probe incrementally seeks the measurements necessary for determining nozzle area through Simpsons Rule.

Referring particularly to FIG. 5, there are shown the broken away ends of connecting links 73, 73' which form the lower end of the probe support means 50. Cylindrical rods 72 connect supporting links 73, 73 and include a connecting link 74 slidably retained thereon for translation along the rods 72. Translation of connecting link 74 relative to rods 72 may be provided by means of a linkage 78, the broken away end of which is connected to an actuator (not shown). Connecting link 74 is rotatably pinned at 76 to two spaced apart lever arms 80, 80'. Lever arms 80, 80 are maintained in opposing spaced relation, and may be rotated about pin 76 by means of linkage 82, the broken away end of which is connected to a second actuator (not shown). A first supporting plate 88 is disposed between the 0pposing lever arms 80, 80 and includes a plurality of roller arms 86, 86 extending from opposing faces of the plate 88. The roller arms 86, 86' are insertedfor rotation and guidance within a pair of cam tracks 84, 84. The support plate 88 also includes a flange 87 about which a connecting rod 92 is rotatably pinned at 90. Rotation of the roller arms 86 along the cam track 84 may be affected by translation of connecting rod 92 through a third actuator (not shown).

A second support plate 1 10 is rotatably pinned at 98 to the first support plate 88. Further connection between support plate 110 and support plate 88 is effected by means of a right angle lever arm 102 which is rotatably pinned at 100 to support plate 88. The right angle lever arm 102 also includes a cam track 104 within which a cam follower 106 projects from the support plate 110. The right lever arm 102 may be rotated about pin 100 by means of linkage 108, the broken away end of which is connected to a fourth actuator (not shown). The dual pencil probe 30 having opposing transducers 32, 32 is coupled to the second support plate 1 by means of a pair of supporting flange members 122 and 122 within which the probe 30 is journalled. The probe 30 journals are arranged so that the center axis of the probe intersects the center axis 96 of pin 98, and is normal thereto.

A flange 112 extends from one face of the support plate 110, and includes a lever arm 114 rotatably pinned at 116 to the top thereof. Lever arm 114 may be rotated about pin 116 by means of linkage 132, the broken away end of which is connected to a fifth actuator (not shown). The actual rotation of lever arm 114 is limited by the wings 118 which abut the stops 120 projecting from the face of support plate 110. Lever arm 114 communicates with the top of the dual pencil probe 30 by means of two connecting links 124 and 126 which are rotatably pinned together at 128. The other end of connecting link 126 is rotatably pinned to lever arm 1 14 at pin 130, whereas the other end of connecting link 124 is fixedly connected to the top of probe 30. A cutaway portion of the previously described nozzle assembly 10, in fixtured relation to the turntable, is also shown in the drawing in order to illustrate how the probe may be moved relative to the nozzle assembly.

Referring now to FIGS. 5 and 6, the initial insertion of the probe 30 may be readily seen. It is to be understood that the actuators are controlled by signals furnished from the computer which is programmed to provide the sequence of operation described below. The solid lines of FIG. 6 illustrate the end position of rotation for the spaced apart lever arms 80, 80 about pin 76. Rotation of the lever arms 80, 80' is accomplished through operation of the actuator connected to the linkage 82 and provides for initial insertion of the probe along the path 37 between two adjacent partitions (A and B) of the nozzle assembly. The path of insertion 37 for probe 30 is an arc wherein a line tangent to the arc in the area between the nozzle partitions A, B may approximate the chord angle of the partitions. As previously discussed, the probe 30 will likely not initially cross the plane of the nozzle area in an orthogonal direction and the ultrasonic beams from the transducers 32, 32 will not initially lie in the plane of the nozzle area. Therefore, a series of incremental corrective adjustments must be made in order to close in on the exact plane of the nozzle area. Rotation of lever arms 80, 80' about pin 76 is continued until the ultrasonic energy beamed from transducer 32 detects the trailing edge 27 of vane B.

The subsequent incremental adjustment of the probe 30 may be better illustrated by referring to FIG. 7 in conjunction with FIG. 5. Operation of the actuator connecting rod 92 translates and rotates rod 92 about pin 90 so as to slide supporting plate between the positions shown by the solid and phantom lines. Cam tracks 84, 84 closely approximate arcuate sections having the same center of curvature as the arcuate path 39. Therefore, movement of plate 88 along cam tracks 84, 84' results in movement of probe 30 along the arcuate path 39 in the manner previously discussed in relation to FIG. 3. Adjustment of the probe 30 into alignment normal to the plane of the nozzle area is accomplished by further incremental rotation in either direction of the spaced apart lever arms 80, about pin 76 in combination with the incremental movement of the plates 88 along the cam tracks 84, 84' in a manner so as to always seek the shortest distance between the line of intersection 35 and the convex surface of vane A.

When the probe axis is aligned normal to the plane of the noule area, the incremental movements are halted and the width measurement may be recorded. Without further disturbing the angle of the probe, the mid-span band, outer band and inner band width measurements may be made by sliding the probe adjusting means 48 along the rods 72, which motion can be accomplished by operation of the actuator connected to linkage 78.

After the three width measurements have been accomplished, the length measurement must be made by rotating the probe 90 about its central axis. Referring back to FIG. 5, there is shown that particular part of the probe adjusting means 48 for rotating the probe about its central axis. When lever arm 114 is rotated about pin 116 through operation of the actuator connected to linkage 132, the connecting link 126 co-acts with the connecting link 124 to rotate the probe about its central axis, thereby moving the probe transducers 32, 32' so that the ultrasonic beams are substantially aligned to a nozzle assembly radius. The center axis 96 preferably extends through the center of transducers 32, 32 so that after the probe has been rotated 90, it may be rocked about the axis 96 to insure that a true minimal length distance is sensed. Rocking the probe about axis 96 is accomplished through operation of the actuator connecting linkage 108 which rotates the right angle lever arm 102 about pin 100. The cam track 104 also pivots about pin causing the cam follower 106 to slide along the cam tracks in a direction away from pin 100. Also, as can be seen from the drawing, rotation of cam track 104 about pin 100 causes a corresponding rotation of cam follower 106 and support plate 110 about axis 96.

The actual rocking motion of the probe may be better understood by referring to FIG. 8 where the phantom lines show the position of the probe after the right angle lever arm 102 has been fully rotated in a counterclockwise direction. The probe is rocked in the above described manner so as to seek the minimum length measurement. When this has been found, the control signal from the computer automatically halts the actuator connecting linkage 108 and the length measurement is recorded. After the three width measurements and one length measurement required for calculating nozzle area have been made, the results are integrated by recorder 66 so as to display the computed nozzle area. The control signal from the computer then operates the actuator connecting linkage 132 to rotate the probe 90 back to its original position. The actuator connecting linkage 82 is also operated to withdraw the entire probe assembly from between the nozzle partitions. The stepping motor then receives a control signal from the computer and rotates the turntable into position for measurement of the adjacent nozzle area.

The actuators which are not shown in FIGS. 8 may be of any type well known to the art. Fluid operated piston actuators would be preferred. The fluid operated piston actuators can be remotely controlled by electrical signals from the computer 68 which may be programmed to sequence the adjusting means 48 through the series of incremental movements required to make each width and length measurement. For a more primitive assembly, the actuators could be manually operated cables where an operator would make sequential movements of the probe from observing the ultrasonic signals as displayed on an oscilloscope. The operator could then record the individual width and length measurements directly from the oscilloscope; however, such an approach would be substantially more time consuming than the previously described programmed method using fluid piston actuators.

Accordingly, while a preferred embodiment of the present invention has been depicted and described in relation to measurements for a nozzle assembly, it will be understood by those skilled in the art that the invention has substantially broader applicability and may be advantageously utilized for a variety of critical measuring operations particularly between spaced apart partitions having irregular surfaces. It will also be understood that many modifications and changes may be made thereto without departing from the inventions fundamental theme.

What is claimed is:

1. An assembly for ultrasonically measuring the minimum distance between the partitions of a nozzle assembly which includes a plurality of circumferentially spaced apart partitions extending in generally radial directions from an inner band to an outer annular band comprises:

a fluid medium within which the nozzle assembly is submersed;

means for generating electrical signals;

a probe having at least two oppositely opposed ultrasonic transducers in electrical connection with the generating means for converting the electrical signals into ultrasonic wave energy, for beaming the ultrasonic waves in substantially opposing directions, and for converting reflected ultrasonic wave energy back into electrical signals;

means for converting the time required for reflected ultrasonic signals to return to the transducers into a representation of distance, and

means for moving the probe between the partitions so that the ultrasonic waves beamed from the opposing transducers are reflected from the spaced apart partitions wherein ultrasonic measuring is first commenced by inserting the probe between the partitions along a near linear path until both ultrasonic transducers receive echo signals whereupon incremental movement of the probe along an arcuate path in combination. with further movement in either direction along the linear path is initiated so as to seek the shortest distance between the nozzle partitions.

2. The assembly of claim 1 wherein the probe moving means is adapted to rotate the probe about its central axis to measure the distance between the bands and wherein there is further included means for integrating the distances into a representation of the minimum nozzle flow area between the partitions.

3. The assembly of claim 2 wherein the means for moving the probe includes: a probe adjusting means for sequencing the probe through a series of incremental movements between adjacent partitions such that the distance measurements of the minimum nozzle flow area may be ultrasonically made, and

a probe support means supporting the adjusting means within the fluid, and wherein the assembly further includes a turntable rotatably disposed within the fluid for receiving and retaining the nozzle assembly, together with means for sequentially stepping rotation of the turntable and nozzle assembly within the fluid so as to bring each nozzle within the area of movement of the probe adjusting means.

4. The assembly of claim 1 wherein:

the generating means includes an ultrasonic pulse generator;

the converting means includes: a range time base having a sawtooth output triggered by the output pulses from the generator, an amplifier for receiving the initial output pulses together with the reflected pulses, and an oscilloscope, the plates of which are connected to the range time base and the amplifier output to provide a visual display of measured distance;

and the entire assembly further includes: a recorder to which the output pulses of the amplifier are connected for integration and calculation of the actual minimum nozzle flow area which may then be recorded on a chart, together with a computer suitably programmed to direct the means for moving the probe through the motions required to make the distance measurements of the minimum nozzle flow area.

5. The assembly of claim 1 wherein the means for moving the probe includes:

a probe support means, and a probe adjusting means having: at least one lever arm rotatably retained with respect to the probe support means wherein the lever arm includes a cam track in one side thereof,

a first support plate disposed for guidance along the cam track,

a second support plate coupling the probe and rotatably connected to the first support plate, and

means for guiding the first plate along the cam track wherein initial insertion of the probe between two spaced apart partitions along the near linear path is accomplished by rotation of the lever arm, and subsequent alignment of the probe normal to the plane of minimum area between the partition is accomplished by cooperatively combining incremental movements of the first support plate along the cam track with rotation of the lever arm so as to seek the shortest distance from the surface of one partition to the surface of the opposing partition.

6. The assembly of claim 5 including means for translating the probe while maintaining the probe normal to the plane of minimum area so as to detect a variation in distance between partitions and further including means for rotating the probe about its central axis while still maintaining the probe normal to the plane of minimum area. 

1. An assembly for ultrasonically measuring the minimum distance between the partitions of a nozzle assembly which includes a plurality of circumferentially spaced apart partitions extending in generally radial directions from an inner band to an outer annular band comprises: a fluid medium within which the nozzle assembly is submersed; means for generating electrical signals; a probe having at least two oppositely opposed ultrasonic transducers in electrical connection with the generating means for converting the electrical signals into ultrasonic wave energy, for beaming the ultrasonic waves in substantially opposing directions, and for converting reflected ultrasonic wave energy back into electrical signals; means for converting the time required for reflected ultrasonic signals to return to the transducers into a representation of distance, and means for moving the probe between the partitions so that the ultrasonic waves beamed from the opposing transducers are reflected from the spaced apart partitions wherein ultrasonic measuring is first commenced by inserting the probe between the partitions along a near linear path until both ultrasonic transducers receive echo signals whereupon incremental movement of the probe along an arcuate path in combination with further movement in either direction along the linear path is initiated so as to seek the shortest distance between the nozzle partitions.
 2. The assembly of claim 1 wherein the probe moving means is adapted to rotate the probe about its central axis to measure the distance between the bands and wherein there is further included means for integrating the distances into a representation of the minimum nozzle flow area between the partitions.
 3. The assembly of claim 2 wherein the means for moving the probe includes: a probe adjusting means for sequencing the probe through a series of incremental movements between adjacent partitions such that the disTance measurements of the minimum nozzle flow area may be ultrasonically made, and a probe support means supporting the adjusting means within the fluid, and wherein the assembly further includes a turntable rotatably disposed within the fluid for receiving and retaining the nozzle assembly, together with means for sequentially stepping rotation of the turntable and nozzle assembly within the fluid so as to bring each nozzle within the area of movement of the probe adjusting means.
 4. The assembly of claim 1 wherein: the generating means includes an ultrasonic pulse generator; the converting means includes: a range time base having a sawtooth output triggered by the output pulses from the generator, an amplifier for receiving the initial output pulses together with the reflected pulses, and an oscilloscope, the plates of which are connected to the range time base and the amplifier output to provide a visual display of measured distance; and the entire assembly further includes: a recorder to which the output pulses of the amplifier are connected for integration and calculation of the actual minimum nozzle flow area which may then be recorded on a chart, together with a computer suitably programmed to direct the means for moving the probe through the motions required to make the distance measurements of the minimum nozzle flow area.
 5. The assembly of claim 1 wherein the means for moving the probe includes: a probe support means, and a probe adjusting means having: at least one lever arm rotatably retained with respect to the probe support means wherein the lever arm includes a cam track in one side thereof, a first support plate disposed for guidance along the cam track, a second support plate coupling the probe and rotatably connected to the first support plate, and means for guiding the first plate along the cam track wherein initial insertion of the probe between two spaced apart partitions along the near linear path is accomplished by rotation of the lever arm, and subsequent alignment of the probe normal to the plane of minimum area between the partition is accomplished by cooperatively combining incremental movements of the first support plate along the cam track with rotation of the lever arm so as to seek the shortest distance from the surface of one partition to the surface of the opposing partition.
 6. The assembly of claim 5 including means for translating the probe while maintaining the probe normal to the plane of minimum area so as to detect a variation in distance between partitions and further including means for rotating the probe 90* about its central axis while still maintaining the probe normal to the plane of minimum area. 